Wireless communication between mobile nodes has become increasingly popular. There are essentially two techniques used for linking nodes in wireless networks. The first uses existing cellular networks, which are essentially systems of repeaters wherein the transmitting or originating node contacts a repeater and the repeater retransmits the signal to allow for reception at the destination node. The obvious drawbacks to the cellular systems include significant infrastructure costs and geographic limitations. Because of the significant infrastructure costs, it is not practical to have cellular networks in all areas. Furthermore, in times of emergency, such as earthquake, fire, or power interruption the cellular network can become disabled in the precise location where it is needed most.
The second technique for linking nodes is to form a wireless ad-hoc network among all users within a limited geographical region. In this situation, each user participating in the ad-hoc network should be capable of forwarding data packets and participating in ascertaining if the packet was delivered from the original source to the final destination. The wireless ad-hoc network has a number of advantages over cellular networks. First, the wireless ad-hoc network is more robust, in that it does not depend on a single node, but rather has a number of redundant, fault tolerant, nodes, each of which can replace or augment its nearest neighbor. Additionally, the ad-hoc network can change position and shape in real time.
Various routing algorithms have been proposed for wireless ad-hoc networks in the literature. These algorithms are mainly focused on establishing and maintaining routes while components of the network undergo frequent and unpredictable connectivity changes. The implicit assumption in most of the earlier work on routing protocols is that nodes' transmit powers are fixed. Power control is known in the context of cellular systems and satellite systems. Thus, one drawback of the versatile ad-hoc network is power consumption. Conventional wireless ad-hoc networks have nodes that generally transmit at a single power level, regardless of the distance that the signal will traverse. Transmitting with too much power is costly in terms of node resources and can cause unwanted interference to nodes engaged in reception of other signals. Thus, it would be desirable to have a power management scheme that reduces power consumption, enhances data throughput, and reduces demand for node resources traditionally allocated for data reception and transmission.
A need exists in the art for a method and apparatus with reduced power consumption, enhanced data throughput, and reduced demand for node resources traditionally allocated for data reception and transmission.